Timers

I have used two timers in my system but since i have implemented this two timers, i am getting random error messages thrown from any part of the systemn this didnt happen before the timer were implemented. So i suspecting that at some point both timers are interfering with eachother and therefore causing this problems.

Is there anyway in Java to control the two timers? i.e. dont sttart the other timer until one timer is finished? or any other ideas that might stop this problem.